The ammonium hydroxide is a catalyst. The aluminum reacts with the water VERY SLOWLY to form aluminum hydroxide and hydrogen gas. The speed at which it occurs is just ridiculously slow. There are no visible effects on the aluminum for weeks, we're talking YEARS. I've hooked it up in an indirect reaction to harvest electrical current, and though you get almost a volt, the current is in micro amps.

its also known as ammonia water, ammonical liquor, ammonia liquor, aqua ammonia or aqueous ammonia

any of those ring a bell?

They all ring a bell.Ammonium hydroxide still doesn't exist.Measure the elctrical conductivity of the stuff and you find it's a bit short on ions. If you look at the raman spectrum you find there's nothing new covalent there either.

John, you're being a bit of a pedant. While it's true that ammonium hydroxide has never been isolated, most aqueous solutions of ammonia are still sold under the name of ammonium hydroxide. It's annoying, but true.

So perhaps if we re-word the question "does ammonia in water, which is usually called ammonium hydroxide despite the fact it doesn't actually form ammonium hydroxide, react with aluminum?", then you'll answer the poor fellow's question?

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Hey guys m thinking of using aluminum in an ammonia/water solution heat exchanger. Would it be a problem. Is there any specific grade of aluminum alloys which i can use to prevent corrosion if it occurs.

NH3 + H2O NH4+ + OH−.In a 1M ammonia solution, about 0.42% of the ammonia is converted to ammonium, equivalent to a pH of 11.63. The base ionization constant is

Kb = [NH4+][OH-]/[NH3] = 1.8×10−5

It can't exist as a solid of course but it does exist in aqueous form.

The ammonium hydroxide is a catalyst. The aluminum reacts with the water VERY SLOWLY to form aluminum hydroxide and hydrogen gas. The speed at which it occurs is just ridiculously slow. There are no visible effects on the aluminum for weeks, we're talking YEARS. I've hooked it up in an indirect reaction to harvest electrical current, and though you get almost a volt, the current is in micro amps.

In exactly the way which I stated earlier."Ammonium hydroxide still doesn't exist.Measure the elctrical conductivity of the stuff and you find it's a bit short on ions. If you look at the raman spectrum you find there's nothing new covalent there either."

Did you not see it, or did you not understand it?

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Ammonia is a base- it's the lone pair that does it. What's to explain?

A solution marketed as, say 50% ammonium hydroxide is about a thousand times less concentrated than the claim. That's wrong enough to count as practically non existent.
Also, ammonium ions are present and hydroxide ions are present (albeit damnably few of them) but there's no compound present that you could sensibly call ammonium hydroxide.

Edited by John Cuthber, 3 March 2012 - 02:59 PM.

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If you dissolve ammonia in water, you will get some hydroxide ions. The counter ions will be ammonium ions. It may not be much, but it is still present enough to be concluded that ammonium hydroxide is a (marginal) component of the solution- just because the equilibrium lies hard in favour of the molecular species doesn't mean the ions cannot exist at all. I don't see any reasonable way that can be denied without grossly changing acid/base (or even lewis) theories. If you can show -OH can magically exist on its own in such a case I will gladly eat my words.

From what the product of 'theoretical ammonium hydroxide' and aluminum are, to the debate whether ammonium hydroxide exists or not. Haha. It's actually not with the name. It is the reaction of ammonia and water that there is a production of ammonium ion and hydroxide ion (though some part of the hydroxide ion production is due to ionization of water itself). OF course both ions exist but as I have said it is not with the name. There is no such evidence that ammonium ion clings to the hydroxide ion. They coexist in solution. In the question whether what would be the product, I haven't tried putting aluminum to ammonia solution. But most probably, aluminum hydroxide will be produced (I just don't know if it would really take years).

First of all to address John. "Ammonium hydroxide" is employed as a trivial name so arguing that it is not an isolated compound for the point of making a snide remark is fairly juvenile. Also, here- it is called "ammonium hydroxide solution" anyway so your argument doesn't even hold true in such situations.

As for ammonia and aluminium, I have no specific idea- but the presence of hydroxide may account for silimilar reactions as NaOH. If this is true, I don't think I would agree with it being a catalytic reaction (not unless the hydroxide is replaced). It is possible you might produce an ammonium/aluminium complex? So I don't know if you would yeild aluminium hydroxide anyway (note that reaction with NaOH gives sodium aluminate not aluminium hydroxide- maybe a similar reaction occurs (although more slowly)?).

Just to add to this.....currently in the lab trying to reduce the solvent content of a litre of solution made to pH 10 with ammonium hydroxide solution. During evaporation some Al foil hit by the gas turned an nice black colour and smelt nicely of NH3. No time or reason to analyse it but while looking for the reaction I found this forum.....hope it helps in any kind of small way.

Also John...if something is labeled 'Nujol' then one can refer to it as Nujol...if something is labeled as 'Borax' one can refer to it as Borax. This solution is labeled 'Ammonium Hydroxide Solution' hence that is how I shall refer to it. If op had said 'I mixed ethylene with...' would you have said 'Ethylene doesn't exist!! I know only of Ethene!!' of course not. Stop being a tool.

Nujol is a perfectly good name for the stuff it represents. So is ethylene.
On the other hand ammonium hydroxide is outrightly misleading.
A bottle labelled as 50% ammonium hydroxide contains the ions equivalent to about 0.05% ammonium hydroxide.
Would you be happy with that in any other context?

It's not that it isn't isolated that's the problem. The issue is that it's about 99.9% not there.

I'm perfectly happy with the outdated names but I'm sure you agree that they are not helpful except to a historian.
Salts of lemon is pretty unhelpful (never having been near the yellow citrus fruit) and, in much the same way, killed spirits was never really alive.
Thankfully the preparation of "oil of Dutch chemists" doesn't involve alchemists from the Netherlands any more that advocaat is made from lawyers.

We have ditched most of the silly names- why keep this one?
It also seems odd to say "Also, here- it is called "ammonium hydroxide solution" anyway "
It was indeed called that in your post- but not in the original one to which I was responding, and I don't do time travel

" It is possible you might produce an ammonium/aluminium complex? "
I'm not saying it's impossible, but a complex between two positively charged ions would seem unusual.

And it's just as well that tools are, by definition, useful or someone might interpret "Stop being a tool. " as an ad hom which would be particularly unfortunate in a first post.

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